There is often a desire to provide a part of an absorbent product with differing degrees of elastic extension. For example, in the waist region a strip of elastic material is often placed between the top and back sheet having been given a pretension of some 30 to 80%, in order to provide an elasticized waist portion. Similarly, elastic side flaps, with a high degree of elasticity (i.e. able to be extended by a large distance elastically) and including an attachment means at the outer end of each flap, may be provided on one waist portion of an absorbent product for releasable attachment to a second waist portion.
The presence of an elasticized waist and elasticized side flaps requires differing elastic material portions to be handled and applied in a series of manufacturing operations. As a solution to this inconvenience, a single elastic strip member of high elasticity may instead be used to span across both the waist and end flaps, whereby the entire waist band and the end flaps are both imparted with a high degree of elasticity. However, since the waistband is not normally stretched to the available extent of this high degree of elasticity, the waist band material where the elastic strip member is attached will generally comprise very coarse gathers. The presence of these coarse gathers may affect either the comfort and/or the containment characteristics of the product. Additionally, when a highly stretched elastic material is attached in the waistband, a greater amount of material is required in the top sheet and/or back sheet in order to produce any given size of waist area, since the coarse gathers require a significant amount of top sheet and/or back sheet material.
The invention seeks to overcome the above problems, whereby individual areas of an absorbent product can be provided with differing degrees of elasticity such that differing areas can be stretched elastically by differing amounts, without resorting to the use of different elastic members in the different areas of the product.
WO-A-01/87213 discloses elasticated areas such as leg or waist areas, added to absorbent products. The elasticated areas are formed as laminates, in which a nonwoven elastic material is stretched and then fixed between two outer layers of inelastic material. The resulting laminate is provided with regions of differing elastic tension or in other words differing elastic modulus. This can be achieved for example by using elastic filaments which are separated by a different distance in two different parts of the laminate, or by using a different elastomeric polymeric compounds or mix of elastomers for the filaments in one part of the web compared to another part, or even by choosing different diameter filaments in different parts of the web. The filaments for the different areas of the web are passed over a common series of rollers in order to be stretched by a certain amount before being attached. In this way, all filaments are stretched the same distance. The resulting differently formed areas of the laminate may each be stretched, by different maximum forces up to the maximum extension of the non-elastic material, which thereby provides different characteristics in the same laminate.
Although the resulting laminate in WO-A-01/87213 includes areas of different elastic modulus, this does not concern the problem of providing areas of different elastic strain in a single member.